Abstract: A hologram recording material includes a polymerizable monomer (A) that is active in radical polymerization but is substantially inactive in cationic polymerization, a polymerizable monomer (B) that is active in cationic polymerization but is substantially inactive in radical polymerization, and an initiator system (C) that polymerizes at least one of the polymerizable monomer (A) and the polymerizable monomer (B) through irradiation with light. The polymerizable monomer (A) and the polymerizable monomer (B) each have, in its structure, a moiety selected from the group consisting of aromatic rings, halogen atoms other than a fluorine atom, and sulfur atoms not derived from a cyclic sulfide or a mercapto group. A hologram recording medium includes a recording layer composed of the hologram recording material.

Abstract: The present invention provides a hologram recording material and a hologram recording medium, which are suitable for volume hologram record and can attain high refractive index change, flexibility, high sensitivity, low scattering, environment resistance, that is, storage stability, durability, low dimensional change (low shrinkage) and high multiplicity in holographic memory recording using not only a green laser but also a blue laser. A hologram recording material comprising: a radical photopolymerizable compound; and a matrix which is a dispersion medium for the radical photopolymerizable compound, wherein the radical photopolymerizable compound comprises a (meth)acrylamide derivative represented by the following general formula (I): CH2?CR1—CONR2—CH2—O—R3 (I) wherein R1 represents H or a CH3 group, R2 represents H or an organic group, and R3 represents an organic group having 3 or more carbon atoms in total. A hologram recording medium 11 which has a hologram recording layer 21.

Abstract: The present invention provides a hologram recording material and a hologram recording medium that can stably maintain the shape of a recording layer and achieve high diffraction efficiency. A hologram recording material comprising a photoradical polymerizable compound (A), a photopolymerization initiator (B), and a dispersion medium (C). The medium (C) is selected from the group consisting of: a compound of the formula (I): wherein R11 is a divalent C2-4 hydrocarbon group, R12 and R13 each independently represent a C1-10 hydrocarbon group, k, l, m and n are each independently a number of 0 or more and 5 or less; and a compound of the formula (II): wherein R21 represents a divalent C1-6 hydrocarbon group, R22 and R23 each independently represent a C1-12 hydrocarbon group, and at least one of R22 and R23 represents a C5-12 hydrocarbon group.

Abstract: An optimal recording exposure is determined by varying in the first to nth stages the recording exposure with a write laser beam to record a bright pattern image and a dark pattern image in each stage as the first to nth bright pattern images and the first to nth dark pattern images, respectively; irradiating the respective pattern images with a read beam to detect the intensity of a diffracted beam from the central portion of each image of the bright and dark patterns; calculating Sa1/Sb1=SNR1, . . . , and San/Sbn=SNRn, where Sa1 to San are the intensity of a diffracted beam from the first to nth bright pattern images and Sb1 to Sbn, are the intensity of s diffracted beam from the first to nth dark pattern images; and determining a recording exposure which is given at the SNRmax being the maximum value of the resulting SNR1 to SNRn.

Abstract: The present invention provides a hologram recording material which is suitable for volume hologram record and attains high refractive index change, flexibility, high sensitivity, low scattering, environment resistance, durability, low shrinkage and high multiplicity in holographic memory record using not only a green laser but also a blue laser; a process for producing the same; and a hologram recording medium having the hologram recording material. A hologram recording material comprising: a metal oxide comprising Si and at least one selected from the group consisting of Ta and Zr, as metals, wherein a complexing ligand is coordinated to Ta and/or Zr; and a photopolymerizable compound. The complexing ligand is preferably selected from the group consisting of ?-dicarbonyl compounds, polyhydroxylated ligands, and ?- or ?-hydroxy acids. A hologram recording medium (11) comprising the hologram recording material layer (21).

Abstract: The present invention provides a hologram recording medium which can attain high refractive index change, flexibility, high sensitivity, low scattering, environment resistance, durability, low dimension change (low shrinkage) and high multiplicity in holographic memory record using a blue laser. A hologram recording medium (11) comprising at least a hologram recording material layer, wherein the hologram recording material layer (21) comprises at least a metal oxide and a photopolymerizable compound; and said hologram recording medium has a light transmittance of 50% or more at a wavelength of 405 nm, or a light reflectance of 25% or more at a wavelength of 405 nm.

Abstract: A recording and reading system for a multi-layered optical recording medium includes: a multi-layered optical recording medium including a plurality of recording layers and a single servo layer; and an optical head. The optical head includes a recording and reading objective lens of a signal recording and reading optical system and a servo objective lens of a servo signal detection optical system that are disposed on a common actuator. The recording and reading objective lens is mounted on the common actuator through a minute-drive apparatus so as to be minutely driven in a focusing direction relative to the servo objective lens. When the servo objective lens is focused on the servo layer, a reading light beam is quickly focused on a target one of the plurality of recording layers.

Abstract: A hologram recording material includes a polymerizable monomer (A) that is active in radical polymerization but is substantially inactive in cationic polymerization, a polymerizable monomer (B) that is active in cationic polymerization but is substantially inactive in radical polymerization, and an initiator system (C) that polymerizes at least one of the polymerizable monomer (A) and the polymerizable monomer (B) through irradiation with light. The polymerizable monomer (A) and the polymerizable monomer (B) each have, in its structure, a moiety selected from the group consisting of aromatic rings, halogen atoms other than a fluorine atom, and sulfur atoms not derived from a cyclic sulfide or a mercapto group. A hologram recording medium includes a recording layer composed of the hologram recording material.

Abstract: The present invention provides a hologram recording material which attains high refractive index change, flexibility, high sensitivity, low scattering, environment resistance, durability, low shrinkage, and high multiplicity, and is suitable for volume hologram recording. Also, the present invention provides a hologram recording medium. A hologram recording material comprising: an organometallic compound at least containing at least two kinds of metals, oxygen, and an aromatic group, and having an organometallic unit wherein two aromatic groups are bonded directly to one metal; and a photopolymerizable compound containing at least a monofunctional compound (A) having one polymerizable functional group in the molecule. The hologram recording material may comprise, as the photopolymerizable compound, a polyfunctional compound (B) having two or more polymerizable functional groups in the molecule. A hologram recording medium 11 has a hologram recording material layer 21.

Abstract: The present invention provides a hologram recording material which attains high refractive index change, flexibility, high sensitivity, low scattering, environment resistance, durability, low shrinkage, and high multiplicity, and is suitable for volume hologram recording. Also, the present invention provides a hologram recording medium. A hologram recording material comprising: an organometallic compound at least containing at least two kinds of metals, oxygen, and an aromatic group, and having an organometallic unit wherein two aromatic groups are bonded directly to one metal; metal oxide fine particles; and a photopolymerizable compound. For example, the metal oxide fine particles are selected from the group consisting of silica fine particles, alumina fine particles, titania fine particles, zirconia fine particles, and complex oxide fine particles containing one or more kinds of metal atoms which constitute said four metal oxides. A hologram recording medium 11 has a hologram recording material layer 21.

Abstract: A method for forming an information recording layer including a multilayer stack of reflection hologram layers modulated in the depth direction of a hologram material layer is provided. The method includes: generating a first pair of polarized coherent laser beams and a second pair of polarized coherent laser beams that are incoherent with the first pair; directing the first pair of polarized coherent laser beams to the hologram material layer from opposite sides thereof, respectively, such that the incident angles of the first pair are symmetric with respect to the hologram material layer; directing the second pair of polarized coherent laser beams to the hologram material layer from the opposite sides thereof, respectively, at incident angles different from the incident angles of the first pair; and forming the multilayer stack of reflection hologram layers according to the interference pattern of the first and second pairs of polarized coherent laser beams.

Abstract: An optimal recording exposure is determined by varying in the first to nth stages the recording exposure with a write laser beam to record a bright pattern image and a dark pattern image in each stage as the first to nth bright pattern images and the first to nth dark pattern images, respectively; irradiating the respective pattern images with a read beam to detect the intensity of a diffracted beam from the central portion of each image of the bright and dark patterns; calculating Sa1/Sb1=SNR1, . . . , and San/Sbn=SNRn, where Sa1 to San are the intensity of a diffracted beam from the first to nth bright pattern images and Sb1 to Sbn are the intensity of s diffracted beam from the first to nth dark pattern images; and determining a recording exposure which is given at the SNRmax being the maximum value of the resulting SNR1 to SNRn.

Abstract: A method for evaluating a hologram image recording medium includes: recording continuously a plurality of fine holograms, each being the same in size as an element hologram, on a hologram image recording medium to be evaluated, using either one of a two-beam interference between a reference beam and a signal beam both being a plane wave and a two-beam interference between a reference beam being a plane wave and a signal beam being a spherical wave; reproducing a diffraction image by irradiating the recorded fine hologram with a plane wave; from intensity distribution data based on a captured diffraction image, determining an intensity distribution data array and a diffracted beam intensity Is, the intensity distribution data array having the same shape and size as those of the fine hologram; and when the diffracted beam intensity Is takes on the maximum value Is(max), determining an SN ratio.

Abstract: A photopolymer medium 10 for color hologram image recording, which is formed so that a color image having a high diffraction efficiency can be obtained by exposing the same recording layer to light at a plurality of wavelengths, includes a recording layer 14 that has a recording sensitivity to light in two wavelength regions of a wavelength ?1 and a wavelength ?2. This recording layer 14 is formed from a material in which a transmittance T1 of light at the wavelength ?1 and a transmittance T2 of light at the wavelength ?2 of the recording layer before recording are both less than 80%, T1<T2 is satisfied, a transmittance T1after of light at the wavelength ?1 after recording has been performed with light at only the wavelength ?2 satisfies T1after>T1, and 10%<T1after<80%.

Abstract: The present invention provides a hologram recording material which is suitable for volume hologram record and can attain high refractive index change, flexibility, high sensitivity, low scattering, environment resistance, that is, storage stability, durability, low dimensional change (low shrinkage) and high multiplicity in holographic memory record using not only a green laser but also a blue laser. A hologram recording material comprising: a metal oxide matrix; and a photopolymerizable compound which has at least one (meth)acrylamide group as a photo-reactive group, and has a polyalkylene glycol unit represented by the following formula: —(RO)n— wherein R represents a lower alkylene group, and n represents the number of repeating units of alkylene oxide.

Abstract: The present invention provides a hologram recording material and a hologram recording medium that can stably maintain the shape of a recording layer and achieve high diffraction efficiency. A hologram recording material comprising a photoradical polymerizable compound (A), a photopolymerization initiator (B), and a dispersion medium (C). The medium (C) is selected from the group consisting of: a compound of the formula (I): wherein R11 is a divalent C2-4 hydrocarbon group, R12 and R13 each independently represent a C1-10 hydrocarbon group, k, l, m and n are each independently a number of 0 or more and 5 or less; and a compound of the formula (II): wherein R21 represents a divalent C1-6 hydrocarbon group, R22 and R23 each independently represent a C1-12 hydrocarbon group, and at least one of R22 and R23 represents a C5-12 hydrocarbon group.

Abstract: The present invention provides a hologram recording material which is suitable for volume hologram record and attains high refractive index change, flexibility, high sensitivity, low scattering, environment resistance, durability, low shrinkage and high multiplicity in holographic memory record using not only a green laser but also a blue laser; a process for producing the same; and a hologram recording medium having the hologram recording material. A hologram recording material comprising: a metal oxide containing at least Si and Zr as metals, wherein an aromatic carboxylic acid compound is coordinated to Zr; and a photopolymerizable compound. The aromatic carboxylic acid compound is, for example, toluic acid. A hologram recording medium (11) comprising the hologram recording material layer (21).

Abstract: The present invention provides a hologram recording material which is suitable for volume hologram record and attains high refractive index change, flexibility, high sensitivity, low scattering, environment resistance, durability, low shrinkage and high multiplicity in holographic memory record using not only a green laser but also a blue laser; a process for producing the same; and a hologram recording medium having the hologram recording material. A hologram recording material comprising: a metal oxide containing at least Si and Zr as metals wherein a ?-dicarbonyl compound is coordinated to Zr; and a photopolymerizable compound, wherein a mole ratio of the ?-dicarbonyl compound to the Zr atom (?-dicarbonyl compound/Zr ratio) is 2/1 or more and 3/1 or less, and a mole ratio of the Si atom to the Zr atom (Si/Zr ratio) is more than 1/1 and 1.15/1 or less in the metal oxide. A hologram recording medium (11) comprising the hologram recording material layer (21).

Abstract: The present invention provides a hologram recording medium which can attain high refractive index change, flexibility, high sensitivity, low scattering, environment resistance, durability, low dimension change (low shrinkage) and high multiplicity in holographic memory record using a blue laser. A hologram recording medium (11) comprising at least a hologram recording material layer, wherein the hologram recording material layer (21) comprises at least: an organometallic compound having at least a Ti—O bond, and a photopolymerizable compound; and said medium has a light transmittance is 50% or more at a wavelength of 405 nm, or a light reflectance is 25% or more at a wavelength of 405 nm. The organometallic compound is favorably obtained by subjecting an alkoxide compound of the corresponding metal(s) to hydrolysis and polymerization reaction in an organic solvent which neither contains cyclic ether skeleton nor carbonyl oxygen.

Abstract: The present invention provides a process for producing a titanium-containing metal oxide the coloration of which is decreased; a hologram recording material suitable for holographic memory recording using a blue laser, wherein a titanium-containing metal oxide the coloration of which is decreased is used as a metal oxide matrix; a process for producing the same; and a hologram recording medium. A process for producing a metal oxide comprising at least Ti as a metal element, the process comprising: providing an alkoxide compound of Ti to which a glycol other than any geminal diol and any vicinal diol is coordinated; hydrolyzing the alkoxide compound of Ti to which the glycol is coordinated, thereby yielding a precursor of a metal oxide; and advancing polycondensation reaction of the metal oxide precursor, thereby forming the metal oxide.